The present invention relates to a device for centrifuging various samples of a product or a mixture of products which are chemical or biological.
In the field of chemistry or biochemistry, the centrifuging of samples is commonly employed to separate different phases (organic, aqueous) in order to extract and purify particular molecules.
In biology, the centrifuging of samples is often used to separate solid particles (cells or bacteria) held in suspension or even in emulsion in the liquid phase.
During the last thirty years, in the various fields of research in chemistry, in biochemistry or in biology, the trend has been to automate the majority of experimental protocols in order to meet criteria of production, speed, quantity and reliability.
This automation of the protocols is carried out using laboratory robots or analyzers mounted in proximity to the working plane on which said protocols are carried out.
These laboratory analyzers or robots generally comprise three mutually perpendicular axes X, Y and Z for the spatial positioning of a head provided with a liquid suction/dispensing system or provided with a gripping system, or alternatively equipped with these two systems.
The laboratory robot or analyzer can transfer reagents and/or biological solutions from one receptacle to the other, which is positioned at various sites on the working plane whose useful area is on average less than 0.3 m2, with a view to conducting reactions, for example enzymatic or colorimetric reactions.
Automation of the experimental protocols requires the placement of all the elements needed for these protocols, for example the test tubes or other supports, the containers of reagents or samples to be processed, the various accessories, such as water-bath heating systems, cooling apparatus or the like, on the working-plane useful surface which is swept by the head of the laboratory analyzer or robot.
The centrifuging step does not currently form part of the steps of the automated experimental protocols, because the available centrifuging devices are not designed to cooperate with a laboratory robot or analyzer as mentioned above.
This is due to the fact that the currently known centrifuging device has a motor for driving a rotor in rotation, which always stops randomly relative to a given point. Since the laboratory robot or analyzer which is used does not have an integrated visualization system, such a robot or analyzer could not find the samples at a given site after the centrifuging step.
Furthermore, in the known centrifuging devices, the tubes intended to contain the samples to be centrifuged are oriented in a fixed position at a certain inclination relative to the axis of the rotor, so that when the rotor is rotating the samples do not escape from the tubes and the centrifuging concentrates are positioned toward the front of the tubes.
However, as mentioned above, a laboratory robot or analyzer works along three perpendicular axes X, Y, Z and cannot operate along an inclined axis.
It is hence incapable of sucking a part of the centrifuged sample placed in the bottom of the tubes, which are positioned so as to be inclined in the centrifuging rotor.
Lastly, the currently marketed centrifuging devices have external dimensions, and in particular an external height, which prevents them from being put on the working plane of laboratory robots or analyzers.
Consequently, because of the difficulties involved with the centrifuging step in an automatic sequence of steps according to a specific experimental protocol, new separation techniques have recently been developed.
For example, in the field of biotechnology, separation columns based on molecular differentiation as a function of size have been developed.
Other techniques for the replacement of centrifuging consist in using a principle of affinity-binding of molecules on magnetic beads.
These new steps, corresponding to new steps for the replacement of centrifuging, nevertheless have certain problems when they are integrated in an automated experimental protocol.
In the case of separation columns, in particular, it is generally difficult to control the flow rate of the various columns which are placed on a laboratory robot or analyzer.
As regards the use of magnetic beads, these represent a cost which is still significant, and this rules out its integration in large-scale processing of samples.